Networks exist which make it possible to produce music from a jukebox-type device by frequency multiplexing a musical selection on a cable network of the coaxial cable type used to distribute television channels. A device such as this one is known from patent EP 0140593. This patent has the drawback, however, that it requires conversion boxes to demultiplex signals, and it uses a network of the coaxial type involving—for one channel—distribution of the same selection to all stations.
A first object of the invention is to allow the network to distribute as a matter of choice either the same selection to all the devices, or a different selection to each individual device; the selection can be either of the audio or video type.
British patent 2193420 and patent PCT WO 9415416 also disclose audio selection distribution networks requiring telephone lines. Due to the use of these telephone lines, network transmission speeds are limited and a network such as this cannot be used for distribution of video selections requiring a high transmission speed to allow good-quality video reproduction.
PCT patent WO 9415416 discloses use of a telephone line of the ISDN type, but even this type of line—the transmission speed of which is limited to 18 megabits per second—is not sufficient to distribute good-quality video data to a sufficient number of devices.
Finally, another object of the invention is a network in which the costly elements are transferred to the level of the server to reduce the cost of each audiovisual reproduction device, but without detriment to their performance. These costly elements are high-capacity hard disks allowing storage of a sufficient number of data selections, in particular video, and also telecommunication modems with transmission speeds allowing the network to be linked to a central system servicing a plurality of networks.
This object is achieved in an audiovisual distribution system according to the present invention. An audiovisual piece can be played on at least one audiovisual device from among a plurality of audiovisual devices. Each device includes audio or video units for playing a piece. The audio or video units are linked to a central computer server containing optical or magnetic memory for mass storage of a plurality of audiovisual pieces selectable from any of these devices. Each of the audiovisual devices has interactive structure for communication with the user to select a piece or a menu, a payment device, a computer network card, a permanent semiconductor memory containing a multitask operating system including at least one hard disk access management task in which the order to play a piece resulting from a selection is handled as a hard disk sequential access task and declaration of the hard disk as a peripheral corresponding to the network card of the device, in order to allow a request to a server to be sent through the network for processing. The server includes a multitask operating system, a permanent mass memory of the magnetic or optical type, and a network card by which the requests from different devices are received. The operating system processes these disk access requests produced by the devices as actual disk access requests.
Another feature of the invention is that in the operating system of each audiovisual device, the declaration of the telecommunications modem belonging to a telecommunications access task as peripheral corresponds to that of the network card, and when a telecommunications access request is made at the device level, the network card of this device transmits this request to the server which itself has at least one telecommunications modem.
According to another feature, the audiovisual device is assured beforehand by a request that the modem card of the server be available.
According to another feature, the transmission speed of each network card and the buffers of video and audio control circuits are dimensioned to allow exchange of data with a transmission rate sufficient for video animation on a network containing at least eight audiovisual devices.
According to another feature, each audiovisual device has a touch screen and its interface software connected as an interactive means of communication with the user.
According to another feature, the network has as many servers each linked to a hard disk as it does servers corresponding to the number (multiple of eight) of audiovisual devices.
According to another feature, the operating system of each server is linked to a switching device making it possible to decide whether the data supplied in response to the request of one network device are given to all the network devices or only to those devices which transmitted a request.
According to another feature, the server is equipped with structure for audio or video performance of a piece, a payment device, and structure for interactive communication with a user or network manager.